Why can't I master the F major!? I just can't get the pad of my index finger to fret both the B and E strings at the same time.

I think that the E string is giving me the most trouble. I just can't get it to ring true and it just plays flat because I'm not able to get both strings fretted at the same time. If I work my finger pad down harder to cover the E it is either pulling the top of the pad off the B or pulling my second and third fingers off the other strings.

Ok, so you've only been playing a short time. The thing you don't want to do is get frustrated and upset.

You're going to have to work at it and practice. Try just using your index finger to barre across the 6 strings. You must be able to successfully do that first. If you can't, there's no sense in adding other fingers into the mess. Make sure your thumb is firmly behind the neck - it MUST give you support and all 6 strings should ring clearly with just the index finger. Once you get this, then start adding in the other fingers. Each time you add a finger to the barre, make sure you play one string at a time. If you find a clunker, make sure you work on your technique to fix the issue, before moving on. If you find your hand getting tired or sore, take a break.

F Major can be a PITA for newbies... Just ask me, I still suck at it. LOL!

KG6_Steven is correct... don't get frustrated. I had a guy tell me that if you get frustrated with anything on guitar, Take a break and practice a different technique, even if only for 10 minutes and go back fresh. You'll find (usually) that you're more open minded and can achieve the skill, be it alternate picking, a scale, or a barre chord, with much less stress.

As for mentioned by others it is hard to explain, how I managed to get around it was by squeezing my thumb against the lower part of the neck (towards to b and e strings) to make it easier to push on the strings with my index.
Hope this helps

It took me five months, 20 mins a day to get the F barre chord down.
I think its the do or die moment for beginner guitarists, it takes patience, practice and discipline but you can do it!
I'm currently working on the G shape barre, check that one out, its a bitch!

If you're trying to play F only barring the top 2 strings, my suggestion is to twist the wrist and bring your elbow into your body, and don't put your first finger "flat" on the 2 strings, you want your first finger to be on its side to the left, this raises the hand so your other fingers can reach the other needed strings.

Stick with it, you will get it eventually. Just remember every single guitar player has gone through this.

F Major is usually voiced in standard tuning as a BAR CHORD. It is not at all uncommon for newer players to have great difficulty this type of chord as it requires a certain level of strength and agility of the fingers that can only be achieved through practice. Providing that you are using the correct technique, the only thing you need to do is KEEP PRACTICING - don't expect to learn to play bar chords overnight!

Here's a tip for you though: F Major is played at the first fret, which is the most difficult location to play a bar chord for a beginner as it requires a larger stretch and more pressure on the strings. To get round this, learn to play the F Major bar chord shape rooted on the 5th fret. Although you'll actually be playing an A Major, it is much easier, and once you learn this, you can very easily play the F Major at the first fret.

EDIT:

Also, I forgot to mention! A "lazy", "open" voicing of an F Major chord is as follows:

E: -x
B: -1
G: -2
D: -3
A: -3
E: -x

Although it's an inversion of F Major, it shouldn't matter too much for a beginner.